<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div {
            /*background-color: #cccccc;*/
            background-color: rgba(0,0,0,0.5);
            width: 200px;
            height: 50px;
            color: red;
            text-align: center;
            line-height: 50px;
        }
    </style>
</head>
<body>
<div>div</div>
</body>
</html>